Hello @hrach , today I stumbled onto another instance of the problem we already discussed in #320 when using

nextras/dbal	v4.0.5
nextras/orm	v4.0.7

Seems that \Nextras\Orm\Mapper\Dbal\DbalMapper::persist() was not fixed and it still contains

$id = (array) $entity->getPersistedId();

which converts the Datetime instance into 3-item array and then tries to use the first part (string) as the PK and fails with Modifier %?dts expects value to be DateTime, string given. again.

I was able to fix it locally with

$id = (array) $entity->getPersistedId();
if ($entity->getPersistedId() instanceof \DateTimeInterface) {
    $id = [$entity->getPersistedId()];
}

I can prepare a pull request with that change in persist(), processMySQLAutoupdate() and remove() if it helps.